Prevention of evaporation losses



April 7, 1931.

H. v. ATWELL 1,800,043

PREVENTION OF EVAPORATION LOSSES 2 Sheets-Sheet l Filed June 20,V 1927 www April 7, l931. y H. v. ATWELI. 1,800,043

PREVENTION OF EVAPORATION LOSSES Filed June 20, 1927 2 Sheets-Sheet 2 yPatentedl Apr. 17, 1931 UNITED STATES PATENT OFFICE HAROLD V. ATWELL, F WRITING, INDIANA, ASSIGNOR T0 STANDARD OIL COMPANY, OF WHITING, INDIANA, A CORPORATION OF INDIANA PREVENTION OF EVAIPORATION LOSSES i Application led .Tune 20,

This invention relates to the prevention of evaporation losses from tanks and storage systems for volatile liquids, particularly petroleum products containing volatile frac- 5, tions.

The invention will be'readily understood from the following description of one embodiment thereof in conjunction with the accompanying drawings, in which- Figure 1 illustrates diagrammatically a suitable installation embodying the invention, and

Fig. 2 is a detail of a modified form of valve control. 1

1,-, Referring to Fig. 1 of the drawings, 10 and i 11 are storage tanks from which vapor pipes 12 and -13 lead to a vapor manifold 14. This manifold leads into a breather bag 15 which may be provided with a superimposed Weight 16 of the type described in application Serial No. 702,029, filed March 26, 1924,

by Robert E. Wilson. A pipe 17 leads into the manifold 14 and av pressure gas line 18 is connected to pipe 17, a valve 19 being lo- 2a cated therebetween. A vacuum line 20 also connects with pipe 17, al valve 21 being interposed therebetween. The pressure gas line 'may be connected to a suitable gas holder or receiver 22 for permanent gases or for more or` less saturated vapors. The line 20 is maintained under vacuum by means of a pump 23 'operated intermittently or continuously, said pump feeding gas from line 2O into a gathering line 24. As illustrated, the

i i line 24 like the line 18 communicates with the gas holder 22,- but it must be understood that the invention is not limited to such arrangement since any suitable lsource may be used to supply.. gas to the line 18, and line 24 may supply the withdrawn vapors .to any suitable plant for further treatment.

The valves 19 `a-nd,21 are preferablyT balanced valves'and are opened and closed in accordance with the degree of inflation or deilation of the'breather bag 15. The stem of 1927. Serial No. 199,963.

the valve 19 is connected to a lever 25 provided with a weight 26 tending to open said valve. The end of the lever 25 remote from weight 26 is provided with a supporting ring 27 adapted to receive a weight 28 of sufficient magnitude to overcome the action of the weight 26 and maintain the valve 19 closed. The weight 28 is provided with a perforation through which passes a cord 29.

The stem of the valve 21 is connected to a lever 30 which is provided with a weight 31 which tends to keep the valve 21 closed. The other end of the lever 30, remote from weight 31 is provided with a ring 32 adapted to receive a weight. 33 which is sucient to overcome the action of the weight 31 and serves to maintain the valve 21 open. The weight 33 is perforated and the cord 29 passes therethrough. Below? the weights 28 and 33 the cord 29 is provided with a. button or projection 34 adapted to engage the weight 33 when the cord moves upwards, thereby lifting said weight oli the ring 32 and allowing the valve 21 to close. On 'further upward movement of the cord 29 the weight 33 is adapted t'o engage the Weight 28 and lift it off the ring 27, the ring 27 being larger than the weight 33 for this purpose. Then this happens, the valve 19 opens. When the cord 29 descends, the weight 28 becomes reseated on the'ringl27 thereby closing the valve 19 and when the cord 29 has descended. so that weight 33 becomes seated on the ring 32, the valve 21 opens. The cord 29 passes over pulleys 35 and 36 and is attached to the upper side of bag 15 or a part moving therewith, for example, the weight 16. In order to insure that the Weights 28 and 33 shall register with the rings 27 and 32, the cord 29 is kept taut by passing it over pulleys 37 and 38 and hanging a weight 39 at its end.

The valves 19 and 21 are located at different levels depending upon their time of operation with respect to the degree of inhation or deflation of the breather bag 15. Fig.

1 indicates approximately the relative positions of the valves when it is desired that Ithe valve 21 shall open when the breather lated half way, then the button 34 and the weight 33will occupy a position intermediate the rings 27 and 32 and the valves 19 .and 21 will be closed. The breather bag is now free to function in its normal manner until the bag becomes `inflated to above threefourths full or more, or until it becomes dellated to a one-fourth or less full. Tn the latter event the button 34 on the cord 29 will .lll

move upwards with the weight 33 and raise the weight 28 off its ring. Thereupon the weight 26 will eliect theopening of the valve 19 and will allow gas from the pressure line 18 to enter into the bag until itbeconies inflated to one-fourth. Thereupon the weight 28 will resume its position on the ring 27 and vapors will be withdrawn through the Vacuum line until the excessive amount ofl y vapors has been removed from the system.

Referring to Fig. 2, 19 and 21 are valves corresponding to the valves 19 and 21 of Fig. 1 These valves communicate with line 17 which is connected to a breather bag system as in Fig. 1. Each of the valves 19 and 21 are adapted to be maintained closed by the weights 40 and 41 respectively mounted on the pivoted levers 42 and 43. The opposite4 ends 44 and 45 of these levers bear upwardly` against cams 47 and v.48 respectively. The Vcams 47 and` 48 are xedly mounted and carry pinions 49 and 50 which are adapted toco-operate with the racks 51 and 52 respectively which are slidably7 mounted. At oneendfthe racks 51 and 52 carry rollers 53 and 54, while at their other end areA provided springs 55 and 56.which abut against the heads 57 and 58 of said racks so as to push them toward the right as viewed in Fig. 2. When the racks are thus pushed to the full extent, the cams 47 and 48 permit the Valves 19 and 21 to remain closed.

The cord 29 corresponds tothe cord 29 of Fig. 1. This cord passes around a lightA drum 59 which is associated with the valve 19 and then passes over another drum 60 associated with valve 21. The cord 29 passes over these drums in opposite directions for a purpose which will hereinafter appear. The cord 29 extends from the drum 60 over suitable pulleys and is provided with a weight 39 at its end. The drums 59 and 60 are mounted upon threaded shafts 61 and .62, being themselves internally threaded correspondingly. These drums are relatively long with respect to their degree of movement, their lengths and such ranges being approximately equall The rollers 53 and 54 are located so that they come in contact with the ends of the drums 59 and 60, under predetermined (circumstances, so that the racks 51 and 52 are pushed inwardly against the opposition of the springs 55 and 56, thereby yrotating the cams 47 and 48 to open the valves 19 and 21. As illustrated, the rollers 53 and 54 are adapted to enter into cooperation with the ends of the drums 59and (iO-when said drums advance to the left, as shown in Fig. v2, until approximately 35% of their tra-vel remains available on the left.

As illustrated, the cams 47 and 48 are such that the distance from the axis to the periphery increases along the periphery when passing counterclockwise from point A to B and such distance remains constant when passingin the same manner from B to C. Ac- A and C. The ratio of the angle from A to B to' the angle from B to C may suitably be about 4:3.

The operation is substantially the same as described in connection with Fig. 1 with the exception that the valves 19 and 21 open gradually. Starting from the position illustrated in Fig. 2, which corresponds to approximately half inflation of the bag, and assuming that v,the bag i's inliating, then the cord 29 passes downwards causing the drums 59 and 60 to rotate clockwise and counterclockwise respectively, when viewed from the left (Fig. 2). The drum 59 accordingly proceeds along the screw threaded shaft 61 to the right and the drum 60 proceeds along the screw threaded shaft 62 to the left until the bag is about 65% inflated, whereupon the drum 60 makes contact with the roller 54 and forces the rack 52 to the left causing the cam 48 to rotate and gradually open the valve 21 If, now, the bag dellates owing to the removal of vapors through the valve 2l', or other causes, the cord`29 ascends thus reversing the movements of the drum 69, the rack 52, and the cam 48. Accordingly, the valve 21 closes gradually and is completely closed when the spring 56 has returned the rack 52 to the position illustrated in Fig. 2. As the bag deflates, the drum 59 proceeds to the left until the bag has reached a stage of inflation, at which time the drum 59 Will make Contact With the roller 53, forcing the -rack 51 to the left in opposition to the spring 55, rotating the cam 47 and gradually opening the valve 19. When the bag has deflated to about 15% full, the point B of the cam 47 will bein cont-act with the Lever 42 and the valve 19 will be fully opened. It the bag further detlates, the valve 19 will be maintained in this condition by the contact of a part of the cam 47 between B and C withthe lever 42. As the bag reinflates, due to the admission of gases or vapors through valve 19', or other` causes, the drum 59 will gradually move to the right and the spring 55 will push the rack 51 in the same direction, causing the cam 47 to rotate in the countercloclrwise direction. When the point B of the cam 47 comes in contact with the lever 42, the valve 19 will begin to close. This closing takes place gradually while the point of Contact of the lever 42 with the cam 47 moves along the periphery from B to A, at which point the valve is completely closed. As the bag deilates further, the drum 59 moves out of contact with the roller 53. i

It is thus obvious that when the bag is in- Iiated to the extent of between 35% and 65%,

. the -breather bag takes care of the vapors which are emitted from or supplied to the liquid storage system. As, however, the breather bag infiates from to 85%, the valve 21 gradually opens and remains open to its full extent if the breather bag iniiates more than 85%. When the bag deflates, the opposite steps take place. Assuming infia tion to an extent greater than 85%,then the valve 21 remains fully open until the bag is 85% full. `As the bag deflates from 85% to 65% full, the valve 21 gradually closes.

When the breather bag deilates to the extent of 35% full, the valve 19 commences to open, is fully opened when the bag is ini'lated to 15%, andvremains open if the bag deiiates to a greater extent.

It is to be understood that the percentages of 15%, 35%, 65%, and 85% full of the breather bag have been selected arbitrarily for the purpose of example only and that the invention is not intended to be limited in any way thereby, since it is obvious that any other degrees of inflation may be selected to define the time when the valves shall begin to open and shall have become fully opened. It will also be readily understood that it is l within the ordinary mechanical skill of those except in so far as included in the accompanying claims.

I claim 1. Valve mechanism adapted for use with a breather bag, and a conduit communicating with the vapor space thereof, comprising a valve in said conduit, a cord movable with the upper side of the breather bag, a drum adapted to co-operate with said cord so as to be rotated thereby, means for imparting a transverse movement to said drum during `its rotation, and means actuated by the transverse movement of said drum to operate said valve.

2. Valve mechanism adapted for use with a breather bag, and a conduit communicating with the vapor space thereof, comprising a valve in said conduit, a cord movable with the upper side of the breather bag, a drum adapted to co-operate with said cord so as to be rotated thereby, means for imparting a transverse movement to said drum during its rotation, a cam actuated by the transverse movement of said drum and means controlled by the cam for operating said valve in accordance with the shape and actuation thereof.

3. Valve mechanism adopted for use with a breather bag, and a conduit communicating therewith, comprising a cord attached to the upper side of the breather bag, a drum adapted to co-operate with said cord so as to be rotated thereby, a threaded shaft on which said drum is mounted so as to be fed thereover by said rotation, a rack adapted to be moved by said drum, and a cam adapted to be rotated by said rack, said cam being adapted gradually to open said valve.

4. Valve mechanism adapted for use with` a storage tank, a breather bag connected therewith, a pressure gas line connected to the vapor space thus constituted, and a vacuum line connected to the vapor space thus constituted, comprising a valve controlling communication between said vapor space and said pressure line, a valve controlling communication between said vapor space and said vacuum line, drums associated with said valves and mounted on screw threaded shafts so as to be moved laterally by rotation thereof, a cord attached to a moving part of said breather bag and adapted to rotate Vsaid drums in opposite directions so that they move laterally in opposite directions, means associated with the valve controlling communication to the vacuum line and adapted to be engaged by one of said drums when said bag exceeds a predetermined stage r"of ingradually and tol remain open as the degree of iniation decreases, v

5. In combinatiomia liquid storage tank, a breather bag, a conduit connecting the vapor space of lthe, storage tank with the 'breather bag, an"aux'iliary vapor storage chamber, a

vacuum line connecting the auxiliary stor-v age chamber and the breather bag, means operable by inflation of the b-reather bag to open communication gradually between theinkl' terior of said bag and the vacuum line as the inflation increases above a certain degree whereby vapors are passed from the breather bag to the vapor storage chamber, apres- 'sure line connecting the auxiliary storage chamber and the breather bag, and means 0perable by deflation of the breather bag to open communication gradually between the interior of said bag and the pressure, line as the deflation increases below a certain degree whereby vapors flow from the vapor storage chamber into the breather bag.

6. In combination, a storage tank for liquids, atbreather bag, an auxiliary vapor storage chamber adapted to maintain a higher pressure therein than the pressure in said breather bag, conduit means connecting the `vapor space of the. storage tank with the breatherbag, conduit means connecting the storage chamber and the breather bag, conduit means provided with pump means and adapted to force vapors from said breather bag into said storage chamber, means operable by inflation' of the breather bag to open communication between the interior of the bag and the third-named conduit means when the inflation of the bag increases above a cer tain degree, and means operable by deflation of the breather bag to open communication between the interior of the bag and the second-named conduitmeans as the deliation increases below a certain degree whereby vapors flow from'l the auxiliary vapor storage chamber into thebreather bag.

7. yIn combination, a storage tank for ,'liquids, a breather bag, an auxiliary vapor storage chamber adapted to maintain a higher pressure therein than the pressure in :said

vbreather bag, conduit means connecting the vapor space of# the storage tank with the breather bag, conduit means connecting the 4storage chamber and the breather bag, conduit means rovided with pump means and adaptedto orce vapors from said breatherl bag into said storage chamber, means oper-S able by rinLation of the breather bag to open communication gradually between the in-VV terior of the bag and the third-named conduit means when the inflation of the bag increases above a certain degree, and means operable .by deflation of the breather bag to open communication gradually between the interior of the bag and the second-named conduit means as the deation increases below a certain degree whereby vapors low from the auxiliary vapor storage chamber into the breather bag.

HAROLD V. ATWELL. 

